For notable Pandaren though we don't have much since they are so new but;

Chen Stormstout obviously. Taran Zhu is the leader of the Shado-pan. Liu Lang, as mentioned above, was their most famous adventurer. Then there are the two representatives for the Horde and Alliance, Ji Firepaw and Aysa Cloudsinger. Emperor Shaohao, who was the last emperor of Panderia and saved Pandaria from the sundering of the world. Then there is Lorewalker Cho, who is basically the Brann Bronzebeard of the Pandaren (imo). Last but not least I would mention the three Brewfathers, Quan Tou Kuo the Two Fisted, Ren Yun the Blind, and Xin Wu Yin the Broken Hearted. Not much known about them but considering the importance of brewing to the Panderan and the fact that they were deemed important enough for monuments I would count them as notable.

100 years old on average is the most logical assessment, due to the fact their culture is based upon living your life to the fullest. If they where an ancient race with a lifespan of lets say 500 years, they would not worship life nor its pleasures and only seek to gain knowledge and keep it for preservation just like the Night elfs.

A personal observation is that the pandarians preserve history in form of either scrolls or in the minds of the lorewalkers, while they keep their memories of the ancestors in stone. That is a indication that Pandarian life is short and hard, that's why they want the most pleasure out of life as possible, and hence their brew culture.

For notable Pandaren though we don't have much since they are so new but;

Chen Stormstout obviously. Taran Zhu is the leader of the Shado-pan. Liu Lang, as mentioned above, was their most famous adventurer. Then there are the two representatives for the Horde and Alliance, Ji Firepaw and Aysa Cloudsinger. Emperor Shaohao, who was the last emperor of Panderia and saved Pandaria from the sundering of the world. Then there is Lorewalker Cho, who is basically the Brann Bronzebeard of the Pandaren (imo). Last but not least I would mention the three Brewfathers, Quan Tou Kuo the Two Fisted, Ren Yun the Blind, and Xin Wu Yin the Broken Hearted. Not much known about them but considering the importance of brewing to the Panderan and the fact that they were deemed important enough for monuments I would count them as notable.

I would add the Shado Pan to that list, lorewise they are all exceptional monks.

He who sees his own doom can better avoid its path. He who sees the doom of others can deliver it.

And that doesn't really matter, since it's better to have a number than no number at all. The ability to use the lifespans page on wowpedia (which is from the RPG books) allows Warcraft roleplayers to have some uniformity, so we don't see a lifespan discrepancy of 100-500 years between players. Sure it's not canon, but there is literally no other information on the subject, so we're better off using it, knowing it isn't canon, that risk everyone doing their own thing. That causes chaos and doesn't do anything but cause confusion and, to a more extreme extent, flamewars over who is right, when nobody is.

The Pandaren lifespan is around 400 years I believe, they reach adulthood around 100. I'm not 100% sure but..99% sure. So that's pretty good. I think I read that from an Rpg book so it might not be Canon but it's better than nothing, also read that off Wowpedia.org and wowwiki.com.

Notable monks? Taran Zhu (Shado Pan) and Chen Stormstout (Stormstout Brewmaster Family) Ji Firepaw and Aysa Cloudsinger since..you know, they're the first monks you meet up with and take you to your faction (horde or alliance)